The present invention pertains to a portable air purifier for removing irritating or harmful impurities from the air, and for sterilizing the air by means of ultraviolet radiation. Pollens, lung damaging dust, smoke, bacteria, viruses, dust mites, and a number of other irritants and microorganisms are commonly found in the ambient atmosphere of an enclosed area. The concentration of such irritants and micro-organisms becomes most acute during the winter months, where insulation and the congregation of persons indoors exacerbates the problem of indoor pollution. Persons with a pre-existing condition are especially vulnerable to suffer illnesses and irritation from contacting such pollutants. Persons afflicted with allergies, emphysema, asthma and other respiratory ailments are examples. Persons with lowered, impaired or otherwise compromised immune systems are especially vulnerable to infection from the bacteria and viruses found in the ambient atmosphere. It has been recognized that filtration of air through some air purification means can combat some of the effects of particulate contamination. Electrostatic filters have been employed to this effect in the prior art. Multiplefilter type systems have also been used in conjunction with ultraviolet germicidal radiation, such as that disclosed in U.S. Pat. No. 4,210,429 to Jerome J. Golstein, issued on Jul. 1, 1980. It has long been recognized that pathogens can be destroyed in the air, in water or on exposed surfaces if they are irradiated with ultraviolet light at the wavelength of about 254 nanometers, which is the preferred wavelength for germicidal use of ultraviolet radiation.
The invention relates to a portable air sterilization and filtration apparatus for removing contaminants from the ambient atmosphere with an improved configuration and method whereby the efficacy of a relatively compact unit in removing indoor pollutants and destroying pathogens is enhanced. More particularly, the preferred embodiment of the invention is a free standing, self-contained unit powered from a conventional AC source (although the unit could be operated from storage batteries rather than an AC source); having a housing with a removable front cover, an inlet opening and an outlet opening, filter media to filter an air stream which flows from the inlet opening to the outlet opening; an ultraviolet light source to provide germicidal radiation to the air stream and to a surface of a filter medium, and a motorized fan for maintaining a flow of air through the housing from the inlet opening to the outlet opening. The unit is compact and attractive, and has a high efficiency of air purification and sanitization using a relatively short air
The invention also includes easy access to the filter media and to the ultraviolet light source for periodic inspection, replacement or cleaning, and integrates a safety lock feature whereby the removal of a filter or the removal of an ultraviolet light source would open the power circuit to the ultraviolet light source, preventing accidental irradiation of the user. The power circuit for the ultraviolet light source also activates indicator lights (preferably standard incandescent light bulbs) viewable by the user when the ultraviolet light source is energized. The invention employs a specific, three filter media system to remove contaminants from the air stream generated within the device by the motorized fan. The air stream passes through a sponge filter, a HEPA type filter (high efficiency particulate air filter), which will remove 99.97% of the airborne particles of the size of 0.3 microns or larger, and an activated charcoal filter. It is only after the air stream has been filtered by the successive filter media that it is irradiated to destroy pathogens. The ultraviolet light source is disposed so as to irradiate the downstream side of the activated charcoal filter during operation of the unit to provide germicidal activity to the filter""s downstream surface and to the air stream as the air stream emerges from the filter prior to its discharge through the outlet opening to return to the ambient atmosphere. It is this combination of three-stage filtering and subsequent radiation of the air stream itself together with the downstream side of the last filter medium that results in improved filtration and germicidal activity. The air stream purified by this combination is effectively more pure than that achieved by prior art combinations.
In addition to the improved efficacy of the combination, safety features are employed to prevent accidental irradiation of the user in a variety of circumstances. In particular, easy access is provided to the filter media and to the ultra violet light source for easy inspection, replacement or cleaning. It is therefore possible for a user to accidentally open the unit to inspect the filter media or ultraviolet light source where the ultraviolet light source is turned on and emitting radiation. To prevent this occurrence, if a user opens the front cover to inspect or replace any of filters or the UV light source, and fails to turn off either the main switch or the separate UV light switch, then safety micro-switches are disengaged, interrupting the power supply to the UV light source and causing the UV light source to immediately cease providing radiation. Thus, the user is protected from accidental UV radiation exposure when opening the unit with both power switches in the on position. Another safety feature is incorporated into the filter media docks, where a user may attempt to operate the device with one of the filter media removed or improperly seated in the dock. Safety micro-switches disengage the supply of power to the device if the filters are not properly seated.
Yet another safety feature is a separate power switch for the UV light source, independent of the main power switch for the device which operates the blower. A separate switch enables the user to operate the device for filtration only, and not for UV sanitization. Another alternative is the use of a double viewing window to permit the user to actually observe the UV light source without being exposed to harmful radiation. A double window is employed to effect this, where one window is substantially transparent and the second window is treated to obstruct harmful UV radiation.
In accordance with the present invention, there is provided an improved ultraviolet air purifier that employs ultraviolet radiation to sterilize a filter and the air stream drawn through the purifier;
Another object of this invention is to provide an improved ultraviolet air purifier that employs an indicator light to alert the user when the ultraviolet light sources are energized;
Another object of this invention is to provide for the downstream irradiation of the filter so as to enhance the germicidal effects of the ultraviolet irradiation;
Another object of this invention is to provide a high efficiency filter medium of the HEPA type to maximize the percentage of small particulate matter entrapped by the filter medium;
Another object of this invention is to provide a safety mechanism by which the removal of the filter will interrupt the power circuit to prevent accidental irradiation of the user;
Another object of this invention is to provide a safety mechanism by which the removal of the ultraviolet light sources will interrupt the power circuit to prevent accidental irradiation of the user;
Another object of this invention is to provide for the easy access and replacement of the filter and of the ultraviolet light sources.